Method for transferring nanostructures

ABSTRACT

A method for transferring nanostructures includes providing a growth substrate and a number of nanostructures located on the growth substrate. The nanostructures are transferred by an adhesive layer from the growth substrate to a target substrate. The nanostructures are between the target substrate and the adhesive layer, and at least partial of nanostructures is in contact with a surface of the target substrate. The adhesive layer is covered by a metal layer. The adhesive layer together with the metal layer is separated from the plurality of nanostructures and the target substrate in an organic solvent, wherein the organic solvent permeates into an interface between the adhesive layer and the nanostructures.

RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 201410070671.5, filed on Feb. 28, 2014, inthe China Intellectual Property Office. This application is related tocommonly-assigned application entitled, “METHOD FOR TRANSFERRINGNANOSTRUCTURE”, concurrently filed (Atty. Docket No. US55843).Disclosures of the above-identified applications are incorporated hereinby reference.

BACKGROUND

1. Technical Field

The present application relates to a method for transferringnanostructures.

2. Discussion of Related Art

It is well-known that growing nanostructures by chemical vapordeposition (CVD) highly depends on proper substrates. For example,horizontally aligned single-walled carbon nanotubes (SWCNTs) andlarge-area graphene of high quality can be grown on quartz substratesand copper foils by CVD, respectively. However, it is more desirable tofabricate electronic and optoelectronic devices with nanostructures onsilicon wafers or flexible substrates. Thus, a transfer technology isproposed and developed to transfer the nanostructure from a growthsubstrate to a target substrate.

The transfer technology generally utilizes a sacrificial layer as themedia. The sacrificial layer can be organic materials. Thenanostructures on a growth substrate are first coated with the organicmaterials, an organic layer can be formed. Then the organic layerattached with the nanostructures is separated from the growth substrateand transferred to the target substrate. Finally the organic layer isremoved by dissolving in acetone or by annealing in an argon atmosphere.

However, it may be difficult to completely remove residues of theorganic layer from the nanostructures and the target substrate, whichresulting in poor contact between the nanostructures and thepost-fabricated metal electrodes. Moreover, removing the organic layerby annealing in an argon atmosphere cannot be applied to plasticsubstrates, because the plastic substrates cannot withstand hightemperature.

What is needed, therefore, is to provide a method for transferringnanostructures that can overcome the above-described shortcomings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referencesto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic process flow of one embodiment of a method fortransferring nanostructure.

FIG. 2 shows a scanning electron microscope image of single walledcarbon nanotubes.

FIG. 3 is an optical microscope image of one embodiment of placing afirst composite substructure in an organic solvent for 30's.

FIG. 4 is an optical microscope image of one embodiment of placing thefirst composite substructure in the organic solvent for 60's.

FIG. 5 is an optical microscope image of one embodiment of placing thefirst composite substructure in the organic solvent for 90's.

FIG. 6 is an optical microscope image of one embodiment of placing thefirst composite substructure in the organic solvent for 300's.

FIG. 7 is an atomic force microscope image of one embodiment of a secondcomposite substructure.

FIG. 8 is a transmission electron microscope image of one embodiment ofthe second composite substructure.

FIG. 9 is a transmission electron microscope image of a substructureincluding the target substrate and the nanostructure layer transferredby conventional method.

FIG. 10 is a schematic process flow of another embodiment of a methodfor transferring nanostructure.

FIG. 11 is an optical microscope image of another embodiment of thefirst composite substructure in air.

FIG. 12 is an optical microscope image of another embodiment of thefirst composite substructure in acetone.

FIG. 13 is an optical microscope image of another embodiment of thefirst composite substructure socked into water after taking out from theacetone of FIG. 12.

FIG. 14 is a schematic process flow of yet another embodiment of amethod for transferring nanostructure.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1, a method for transferring a nanostructure layer 22of one embodiment includes steps of:

(S1), providing a growth substrate 10 having a nanostructure layer 22,wherein the nanostructure layer 22 including a plurality ofnanostructures 20 is located on a top surface 102 of the growthsubstrate 10;

(S2), covering the nanostructure layer 22 by an adhesive layer 30;

(S3), separating the adhesive layer 30 from the growth substrate 10through moving the adhesive layer 30 or/and the growth substrate 10, toseparate the nanostructure layer 22 from the growth substrate 10;

(S4), stacking the adhesive layer 30 on a target substrate 40, whereinthe nanostructure layer 22 is between the target substrate 40 and theadhesive layer 30, and the nanostructure layer 22 is in contact with asurface of the target substrate 40;

(S5), placing a metal layer 50 on the first surface 302 of the adhesivelayer 30 to form a first composite substructure 60; and

(S6), placing the first composite substructure 60 in an organic solvent80, and separating the adhesive layer 30 together with the metal layer50 from the nanostructure layer 22 and the target substrate 40, whereinthe organic solvent 80 permeates into an interface between the adhesivelayer 30 and the nanostructure layer 22.

In the step (S1), the top surface 102 of the growth substrate 10 can beflat and smooth. The growth substrate 10 can be a P-type siliconsubstrate, an N-type silicon substrate, or a silicon substrate havingoxide layer disposed thereon. In one embodiment, the growth substrate 10is made of quartz.

The plurality of nanostructures 20 can be directly grown on the topsurface 102 of the growth substrate 10. The plurality of nanostructures20 can be pasted or paved on the top surface 102 of the growth substrate10. The plurality of nanostructures 20 can be parallel or perpendicularto the top surface 102 of the growth substrate 10. An angle can beformed between the plurality of nanostructures 20 and the top surface102 of the growth substrate 10. A thickness of the nanostructure layer22 can be less than or equal to 1 micron. There can be a distancebetween two adjacent nanostructures 20.

The plurality of nanostructures 20 can closely arrange, thus there is nodistance between two adjacent nanostructures 20.

The plurality of nanostructures 20 can be nanomaterial, such as carbonnanotube or graphite. In one embodiment, the plurality of nanostructures20 is a plurality of single walled carbon nanotubes parallel to the topsurface 102 of the growth substrate 10. A method for making theplurality of single walled carbon nanotubes is arbitrary.

In one embodiment, a method for making the plurality of single walledcarbon nanotubes includes steps of:

(S11), annealing a stable temperature-cut (ST-cut) quartz substrate at900° C. for 8 h in O₂;

(S12), depositing a catalyst film with a nominal thickness of 0.2nanometers on a surface of the ST-cut quartz substrate byphotolithography, wherein the catalyst film can be made of iron, cobalt,nickel, or any combination alloy thereof;

(S13), placing the ST-cut quartz substrate with the catalyst film in afurnace, and purging the furnace using 1000 standard cubic centimeter(sccm) of argon (Ar) after ramping up step in air to 700° C., and thenintroducing a flow of Ar (500 sccm) and hydrogen (H₂, 500 sccm); and

(S14), growing the plurality of single walled carbon nanotubes at 850°C. with a flow of methane (CH₄, 500 sccm), H₂ (100 sccm) and Ar (400sccm) for 15 min, wherein the plurality of single walled carbonnanotubes is as shown in FIG. 2.

In the step (S2), the adhesive layer 30 can be made of organic material,such as poly (methyl methacrylate) (PMMA), poly (dimethylsiloxane)(PDMS), or polyimide (PI). In one embodiment, the adhesive layer 30 ismade of PMMA.

An organic material solution can be spin-coated onto a surface of thenanostructure layer 22 away from the growth substrate 10 and form theadhesive layer 30.

In one embodiment, the surface of the nanostructure layer 22 away fromthe growth substrate 10 is spin-coated by PMMA solution and then bakedat 120° C. for 2 min to form a dense film. When two adjacentnanostructures has the distance, the adhesive layer 30 can permeate intothe distance and fill the distance.

The adhesive layer 30 needs to be a continuous film and cover thenanostructure layer 22 or cover each of the plurality of nanostructures20. A thickness of the adhesive layer 30 can be selected according toneed. The thickness of the adhesive layer 30 can be in a range fromabout 100 microns to about 300 microns. In one embodiment, the thicknessof the adhesive layer 30 is in a range from about 150 microns to about250 microns. In one embodiment, the thickness of the adhesive layer 30is 190 microns.

In the step (S3), the adhesive layer 30 is viscous. A combine forcebetween the adhesive layer 30 and the nanostructure layer 22 is greaterthan a combine force between the nanostructure layer 22 and the growthsubstrate 10. Therefore, the adhesive layer 30 together with thenanostructure layer 22 is stripped from the growth substrate 10, whereinthe nanostructure layer 22 is pasted on the adhesive layer 30.

In detail, the adhesive layer 30 is gradually stripped from the growthsubstrate 10 by moving the adhesive layer 30 or/and the growth substrate10. The nanostructure layer 22 is also separated from the growthsubstrate 10 because the nanostructure layer 22 is pasted on theadhesive layer 30. At least partial of the plurality of nanostructures20 is exposed out of the adhesive layer 30.

A method for separating the adhesive layer 30 together with thenanostructure layer 22 from the growth substrate 10 can be chemistry orphysics method, such as cauterizing and removing the growth substrate 10by a chemical solution, or separating the adhesive layer 30 togetherwith the nanostructure layer 22 from the growth substrate 10 by amechanical force. In one embodiment, the adhesive layer 30 together withthe nanostructure layer 22 is separated from the growth substrate 10 inNaOH aqueous solution in 100° C. A molar concentration of the NaOHaqueous solution is 1 mol/L.

In the step (S4), a material and size of the target substrate 40 can beselected according to need. The material of the target substrate 40 canbe silicon, silicon dioxide, or soft polymer. When the target substrate40 is made of polyethylene glycol terephthalate (PET), a thickness ofthe target substrate 40 can be about 70 microns. In one embodiment, thetarget substrate 40 is made of silicon, a surface of the silicon targetsubstrate 40 is oxidized to a silicon dioxide layer with a thickness of300 nanometers.

The adhesive layer 30 is directly pasted on a surface of the targetsubstrate 40, and the plurality of nanostructures 20 is between theadhesive layer 30 and the target substrate 40. At least partial of theplurality of nanostructures 20 exposed out of the adhesive layer 30 isdirectly contacted with the surface of the target substrate 40.

In the step (S5), the adhesive layer 30 has a first surface 302 awayfrom the target substrate 40, and a second surface 304 opposite to thefirst surface 302 and close to the target substrate 40, the metal layer50 is deposited on the first surface 302 of the adhesive layer 30 byelectron-beam evaporation. A material of the metal layer 50 can beselected according to need, such as Au, Ti, Al or Gr. The first surface302 of the adhesive layer 30 is totally covered by the metal layer 50,thus the metal layer 50 needs to be a continuous film. Side surfaces ofthe adhesive layer 30 are not covered by the metal layer 50.

The metal layer 50 cannot totally cover the adhesive layer 30 if themetal layer 50 is too thin. The adhesive layer 30 can hardly be fullyremoved from the nanostructure layer 22 or the target substrate 40 ifthe metal layer 50 is too thick. Therefore, a thickness of the metallayer 50 can be in a range from about 10 nanometers to about 50nanometers. In one embodiment, the thickness of the metal layer 50 is ina range from about 10 nanometers to about 25 nanometers. In oneembodiment, the metal layer 50 is a Ti film with a thickness of 20nanometers.

The first composite structure 60 includes the target substrate 40, thenanostructure layer 22 located on the target substrate 40, the adhesivelayer 30 located on the nanostructure layer 22, and the metal layer 50located on the first surface 302 of the adhesive layer 30. Thenanostructure layer 22 is between the target substrate 40 and the secondsurface 304 of the adhesive layer 30.

In the step (S6), a contact between the second surface 304 of theadhesive layer 30 and the nanostructure layer 22 or the target substrate40 is relatively weaker than a contact between the first surface 302 ofthe adhesive layer 30 and metal layer 50.

Therefore, when the first composite structure 60 is immersed in theorganic solvent 80, the organic solvent 80 initiates from the secondsurface 304 of the adhesive layer 30. When the adhesive layer 30 nearthe second surface 304 is dissolved, the residual adhesive layer 30 canbe fully peeled away from the target substrate 40 with the help of themetal layer 50, leaving clean nanostructure layer 22 on the targetsubstrate 40.

On the one hand, the metal layer 50 is actually to prevent thedissolution of the adhesive layer 30 from the first surface 302 and todissolve the adhesive layer 30 from the second surface 304; on the otherhand, the metal layer 50 increases a mechanical strength of ametal-coated adhesive film. Thus, the adhesive layer 30 is removed inlarge block before the adhesive layer 30 is fully resolved into smallpieces. Therefore, a transferred nanostructure layer 22 on the targetsubstrate 40 is clean with little residue.

The organic solvent 80 can be located in a wide mouth container 90 anddissolve the adhesive layer 30, such as acetone, ether, or methylalcohol. The metal layer 50 and the target substrate 40 are notdissolved by the organic solvent 80. In one embodiment, the organicsolvent 80 is acetone. When the first composite structure 60 is immersedin the organic solvent 80 for a time ranged from about 3 min to about 10min, the metal layer 50 together with the adhesive layer 30 is fullypeeled off from the nanostructure layer 22 and the target substrate 40without external force, to form a second composite structure 70.

Referring to FIGS. 3-6, the target substrate 40 is PET, the metal layer50 is a Ti film with a thickness of 20 nanometers, the adhesive layer 30is PMMA, when the first composite structure 60 is immersed in theorganic solvent 80, with increasing of the time, the Ti film togetherwith PMMA (Ti-coated PMMA) is gradually peeled from the nanostructurelayer 22 and PET substrate. Ti-coated PMMA could be fully peeled offfrom the PET substrate after dipped into acetone solution for 5 min.

The second composite structure 70 includes the target substrate 40 andthe plurality of nanostructures 20 located on a surface of the targetsubstrate 40. The plurality of nanostructures 20 and the targetsubstrate 40 are clean with little metal and adhesive residue, as shownin FIGS. 7 and 8. On the contrary, as shown in FIGS. 9, there is residuein a substructure including the target substrate 40 and thenanostructure layer 22 transferred by a conventional method.

The metal layer 50 can be a resistant layer for preventing the firstsurface 302 of the adhesive layer 30 from directly contacting with theorganic solvent 80. The resistant layer prevents dissolution of theadhesive layer 30 from the first surface 302. A material of theresistant layer can be not dissolved by the organic solvent 80 and notrestricted to metal.

In addition, placing the metal layer 50 on the first surface 302 of theadhesive layer 30 can be omitted. After transferring the nanostructurelayer 22 on the target substrate 40 from the growth substrate 10 by theadhesive layer 30, the nanostructure layer 22 is between the targetsubstrate 40 and the adhesive layer 30. The nanostructure layer 22 is incontact with the second surface 304 of the adhesive layer 30. And then,the organic solvent 80 is dipped into the interface between the adhesivelayer 30 and the nanostructure layer 22 by a tool, such as dropper,funnel. The organic solvent 80 initiates from the second surface 304 ofthe adhesive layer 30. The adhesive layer 30 is peeled off from thenanostructure layer 22 and the target substrate 40, leaving cleannanostructure layer 22 on the target substrate 40.

An embodiment of the method for transferring the nanostructure layer 22is shown where the thickness of the metal layer 50 is greater than orequal to 10 nanometers, and after placing the first composite structure60 in the organic solvent 80, the metal layer 50 together with theadhesive layer 30 is separated from the nanostructure layer 22 and thetarget substrate 40 by an external force, such as a mechanical force,surface tension and buoyancy of water.

The metal layer 50 needs to be the continuous film and cover thenanostructure layer 22 or cover each of the plurality of nanostructures20. In one embodiment, the thickness of the metal layer 50 is in a rangefrom about 15 nanometers to about 125 nanometers. In one embodiment, themetal layer 50 is an Au film with a thickness of 50 nanometers.

When the external force is the mechanical force, after placing the firstcomposite structure 60 in the organic solvent 80, entire surface of themetal layer 50 away from the adhesive layer 30 is pulled by a uniformupward force, or/and entire surface of the target substrate 40 away fromthe nanostructure layer 22 is pulled by a uniform downward force.Therefore, the metal layer 50 together with the adhesive layer 30 isseparated from the nanostructure layer 22 and the target substrate 40.The force can be provided by a tool, such as vacuum chuck.

When the external force is surface tension and buoyancy of water, theorganic solvent 80 needs to have poor mutual solubility with water, suchas acetone. In one embodiment, the organic solvent 80 is acetone.

Referring to FIG. 10, the first composite structure 60 is placed in theorganic solvent 80, a multitude of wrinkles appeared on a surface of ametal/adhesive film, wherein the metal/adhesive film is a wholestructure formed by the metal layer 50 and the adhesive layer 30. Theformation of there wrinkles can be attributed to partial and unevenseparation between metal/adhesive film and the target substrate 40induced by the organic solvent 80 dissolving and penetration. And then,the first composite structure 60 is soaked into water 100 after takingout from the organic solvent 80, the whole wrinkled film can be directlypeeled off from the nanostructure layer 22 and the target substrate 40.The separation in water 100 is caused by the surface tension from water100 and the low solubility between the organic solvent 80 and water 100.Finally, the metal/adhesive film and the organic solvent 80 are removed,to obtain the second composite structure 70 after drying. Wherein, thewater 100 can be located in the wide mouth container 90.

Furthermore, this method can be applied transfer the plurality ofnanostructures 20 grown on the growth substrates 10 with relativelyrough surface, such as graphene on copper foils, because on thoserelatively rough substrates, a thicker metal layer 50 is required toform a continuous film.

FIGS. 11-13 show shapes of the metal/adhesive film of the firstcomposite structure 60, wherein the metal layer 50 is the Au film withthe thickness of 50 nanometers, the adhesive layer 30 is PMMA, theorganic solvent 80 is acetone, and the metal/adhesive film is Au/PMMAfilm. In air, the Au/PMMA film is flat and smooth, as shown in FIG. 11.In acetone, the multitude of wrinkles appeared on a surface of theAu/PMMA film, as shown in FIG. 12. In water, whole wrinkled Au/PMMA filmcan be directly peeled off from the nanostructure layer 22 and thetarget substrate 40, as shown in FIG. 13.

Referring to FIG. 14, a method for transferring the nanostructure layer22 of one embodiment includes steps of:

(S1′), providing a growth substrate 10 having a top surface 102, whereinthe nanostructure layer 22 including a plurality of nanostructures 20 islocated on the top surface 102 of the growth substrate 10;

(S2′), locating an adhesive layer 30 on a base 52;

(S3′), contacting the adhesive layer 30 with the nanostructure layer 22,wherein the adhesive layer 30 and the nanostructure layer 22 are betweenthe base 52 and the growth substrate 10;

(S4′), separating the adhesive layer 30 from the growth substrate 10through moving the base 52 or/and the growth substrate 10, to separatethe nanostructure layer 22 from the growth substrate 10;

(S4′), stacking the adhesive layer 30 on a target substrate 40, whereinthe nanostructure layer 22 is between the target substrate 40 and theadhesive layer 30, and the nanostructure layer 22 is in contact with thesecond surface 304 of the adhesive layer 30 and a surface of the targetsubstrate 40; and

(S5′), separating the adhesive layer 30 together with the base 52 fromthe nanostructure layer 22 and the target substrate 40 by an externalforce in an organic solvent 80, wherein the organic solvent 80 permeatesinto an interface between the adhesive layer 30 and the nanostructurelayer 22.

This embodiment of the method for transferring the nanostructure layer22 is shown where the metal layer 50 is replaced by the base 52, and theadhesive layer 30 together with the base 52 is separated from thenanostructure layer 22 and the target substrate 40 by the external forcein the organic solvent 80.

In the step (S2′), the base 52 cannot be dissolved by the organicsolvent 80. A material of the base 52 can be metal, such as Au, Ti, Alor Gr. The adhesive layer 30 can be formed by spin-coating the organicmaterial onto the base 52. A thickness of the base 52 is greater than orequal to 10 nanometers.

In the step (S5′), on the one hand, the base 52 is actually to preventthe dissolution of the adhesive layer 30 from the first surface 302 andto dissolve the adhesive layer 30 from the second surface 304; on theother hand, the base 52 increases a mechanical strength of the adhesivelayer 30. Thus, the adhesive layer 30 is resolved in large block beforethe adhesive layer 30 is fully resolved into small pieces. Finally, thebase 52 together with the adhesive layer 30 in large block is separatedfrom the nanostructure layer 22 and the target substrate 40 by theexternal force. Therefore, a transferred nanostructure layer 22 on thetarget substrate 40 is clean with little residue. The external force canbe the surface tension and buoyancy of water or the mechanical force.

In summary, the plurality of nanostructures 20 is transferred on thetarget substrate 40 by the adhesive layer 30. And then the organicsolvent 80 permeates into the interface between the adhesive layer 30and the plurality of nanostructures 20. The adhesive layer 30 isdissolved from the second surface 302, to make transferrednanostructures 20 on the target substrate 40 be clean with littleresidue. The method is not need high temperature and can be implementedin room temperature. Moreover, the method is simple.

It is to be understood that the above-described embodiment is intendedto illustrate rather than limit the disclosure. Variations may be madeto the embodiment without departing from the spirit of the disclosure asclaimed. The above-described embodiments are intended to illustrate thescope of the disclosure and not restricted to the scope of thedisclosure.

It is also to be understood that the above description and the claimsdrawn to a method may include some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

1. A method for transferring nanostructures comprising: providing aplurality of nanostructures on a growth substrate; covering theplurality of nanostructures with an adhesive layer; separating theplurality of nanostructures from the growth substrate by moving theadhesive layer or the growth substrate until the plurality ofnanostructures are partially exposed out of the adhesive layer; stackingthe adhesive layer on a target substrate by sandwiching the plurality ofnanostructures between the target substrate and the adhesive layer andplacing exposed portions of the plurality of nanostructures in contactwith the target substrate; covering the adhesive layer with a metallayer; and separating the adhesive layer and the metal layer from theplurality of nanostructures and the target substrate by permeating anorganic solvent between the adhesive layer and the plurality ofnanostructures.
 2. The method of claim 1, comprising covering a surfaceof the adhesive layer away from the target substrate completely with themetal layer.
 3. The method of claim 1, comprising forming the pluralityof nanostructures into a nanostructure layer, a thickness of thenanostructure layer being less than or equal to 1 micron.
 4. The methodof claim 1, comprising forming the nanostructures comprising carbonnanotubes or graphites.
 5. The method of claim 1, wherein the metallayer comprises Au, Ti, Al or Gr.
 6. The method of claim 1, wherein athickness of the metal layer is in a range from about 10 nanometers toabout 50 nanometers.
 7. The method of claim 1, wherein the metal layeris made of Ti film with a thickness of 20 nanometers.
 8. The method ofclaim 1, wherein the organic solvent is acetone, ether, or methylalcohol.
 9. The method of claim 1, wherein the adhesive layer is made ofpoly (methyl methacrylate), poly (dimethylsiloxane), or polyimide. 10.The method of claim 1, wherein the organic solvent is acetone, theadhesive layer is made of poly (methyl methacrylate), and the metallayer is made of Ti.
 11. A method for transferring nanostructurescomprising: providing a plurality of nanostructures on a growthsubstrate; transferring the plurality of nanostructures by an adhesivelayer from the growth substrate to a target substrate by placing theplurality of nanostructures between the target substrate and theadhesive layer, and the plurality of nanostructures being partially incontact with the target substrate; covering the adhesive layer with aresistant layer; and separating the adhesive layer and the resistantlayer from the plurality of nanostructures and the target substrate bypermeating in an organic solvent between the adhesive layer and theplurality of nanostructures.
 12. The method of claim 11, wherein theresistant layer is made of metal.
 13. The method of claim 11, wherein athickness of the resistant layer is in a range from about 10 nanometersto about 50 nanometers.
 14. The method of claim 11, comprising formingthe nanostructures comprising carbon nanotubes or graphites.
 15. Themethod of claim 11, wherein the adhesive layer is made of poly (methylmethacrylate), poly (dimethylsiloxane), or polyimide.
 16. The method ofclaim 11, wherein the organic solvent is acetone, ether, or methylalcohol.
 17. The method of claim 11, wherein the organic solvent isacetone, the adhesive layer is made of poly (methyl methacrylate), andthe metal layer is made of Ti.
 18. A method for transferringnanostructures comprising: providing a plurality of nanostructures on agrowth substrate, wherein the plurality of nanostructures is parallel toa top surface of the growth substrate; transferring the plurality ofnanostructures by an adhesive layer from the growth substrate to atarget substrate by placing the plurality of nanostructures between thetarget substrate and the adhesive layer, and the plurality ofnanostructures being partially in contact with a surface of the targetsubstrate; and separating the adhesive layer from the plurality ofnanostructures and the target substrate be permeating an organic solventbetween the adhesive layer and the plurality of nanostructures, anddissolving the adhesive layer from the interface.
 19. The method ofclaim 18, comprising forming the nanostructures comprising carbonnanotubes or graphites.
 20. The method of claim 18, wherein the organicsolvent is acetone, the adhesive layer is made of poly (methylmethacrylate).